664787 has 4 divisors (see below), whose sum is σ = 667920. Its totient is φ = 661656.

The previous prime is 664777. The next prime is 664789. The reversal of 664787 is 787466.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 664787 - 2⁴ = 664771 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 664787.

It is not an unprimeable number, because it can be changed into a prime (664789) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1223 + ... + 1680.

It is an arithmetic number, because the mean of its divisors is an integer number (166980).

2⁶⁶⁴⁷⁸⁷ is an apocalyptic number.

664787 is a deficient number, since it is larger than the sum of its proper divisors (3133).

664787 is a wasteful number, since it uses less digits than its factorization.

664787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3132.

The product of its digits is 56448, while the sum is 38.

The square root of 664787 is about 815.3447123763. The cubic root of 664787 is about 87.2758671863.

The spelling of 664787 in words is "six hundred sixty-four thousand, seven hundred eighty-seven".